PROJECT SUMMARY/ABSTRACT Pain is common in later life and has high personal, social, and economic costs. With the aging of large, post- World War II ?baby boom? cohorts, the prevention and effective treatment of late-life pain have become high public health priorities. However, current research on late-life pain is limited in two regards. First, it continues to focus mainly on biological and psychological explanations for older adults' pain; almost nothing is known about the social and physical environmental determinants of late-life pain. Second, it is focused primarily on older adults' immediate pain as it occurs in day-to-day living situations and clinical healthcare encounters, neglecting to examine the longitudinal, within-person course of late-life pain. We propose that an ecological model of late- life pain can help pain and aging research expand beyond these paradigmatic boundaries to advance knowledge regarding the determinants, prevention, and effective treatment of late-life pain. The purpose of this project is to develop and test the reproducibility of an ecological model of late-life pain through secondary analyses of data from two existing longitudinal studies of late-life health. Borrowing from the public health- based ecological model of health, we have identified the key constructs, measures, and hypothesized relationships to include in a preliminary ecological model of late-life pain. To test our model, we will use two 3- wave longitudinal cohorts from the Longitudinal Late-Life Health (LLLH) study (n=1,884). We will first test the hypothesis that social and physical environmental stressors have significant contemporaneous effects on late- life pain using regression analyses of LLLH cross-sectional data; next, we will conduct multilevel linear modeling with time-varying covariates to determine the influence of time-varying social and physical environmental stressors on participants' within-person levels and rates of change in pain over 10- to 13-year intervals. Second, to begin to understand mechanisms through which environmental stressors influence late- life pain, we will conduct single- and multi-level mediation analyses to demonstrate the mediating role of negative affective responses in the relationship between environmental stressors and pain. Third, to test the proposition that older adults' personal resources can reduce the impacts of heightened environmental stressors on pain outcomes, we will conduct regression analyses, with interaction terms, of LLLH cross- sectional data, and two-group simultaneous latent variable growth modeling of LLLH longitudinal data. To strengthen the inferences we can draw from the findings above, we will attempt to reproduce them in an 8- year, 3-wave longitudinal cohort (n=7,703) from the national Health and Retirement Study. Results of this project will push the paradigmatic boundaries of current pain and aging research and lay the foundation for future clinical research aimed at improving older adults' pain treatment outcomes and courses of late-life pain.